Field of the Invention:
The invention relates to a method for fast recognition of a wearer's own voice for a hearing aid and to a corresponding apparatus. The apparatus receives audio signals from at least two acoustoelectric transducers and has a first filter and a second filter for spatial separation that are connected for signaling purposes to the acoustoelectric transducers.
Hearing aids are portable hearing apparatuses that are used for looking after the hard of hearing. In order to meet the numerous individual needs, different designs of hearing aids are provided, such as behind the ear hearing devices (BTE), hearing devices with an external receiver (RIC: receiver in the canal) and in the ear hearing devices (ITE), e.g. including concha hearing devices or canal hearing devices (ITE, CIC). The hearing devices listed by way of example are worn on the outer ear or in the auditory canal. Furthermore, there are also bone conduction hearing aids, implantable or vibrotactile hearing aids available on the market. These involve the damaged hearing being stimulated either mechanically or electrically.
Hearing aids basically include the primarily important components of an input transducer, an amplifier and an output transducer. The input transducer is normally an acoustoelectric transducer, e.g. a microphone, and/or an electromagnetic receiver, e.g. an induction coil. The output transducer is for the most part implemented as an electroacoustic transducer, e.g. a miniature loudspeaker, or as an electromechanical transducer, e.g. a bone conduction receiver. The amplifier is usually integrated in a signal processing device. Power is usually supplied by a battery or a rechargeable storage battery.
Hearing aids or the ear shells thereof firstly seal the auditory canal completely or partially, and secondly hearing aids preferably pick up airborne sound via their microphone, while body-borne sound is preferably rejected. The voice of the hearing device wearer is perceived differently than from the environment, however, precisely on account of the body-borne sound.
For a hearing device wearer, the fact that primarily airborne sound is amplified results in an altered and unfamiliar perception of the wearer's own voice. In addition, the sealing of the auditory canal by the hearing aid leads to an effect that is termed occlusion and that likewise distorts perception. To process the wearer's own voice and external audio sources differently and to approximate the hearing habits of a person without a hearing aid, it is necessary to recognize the own voice of the hearing device wearer quickly and reliably.
Commonly assigned U.S. Pat. No. 8,873,779 B2 and its counterpart German published patent application DE 10 2011 087 984 A1 discloses a method for recognizing the own voice of the wearer for a hearing aid.
Published patent application US 2006/0262944 A1 discloses a communication apparatus that has a filter and that recognizes the own voice of a wearer.
International patent application publication WO 2004/077090 A1 and U.S. Pat. No. 7,512,245 B2 describe a method for recognizing the own voice of the wearer of a communication device having at least two microphones, wherein in one embodiment the individual microphone signals are each supplied to different filters, the coefficients of which are determined by an optimization method such that the distance of the spectral power density of a voice signal of the wearer from the spectral power density of a representative far field signal is maximized. The microphone signals are each filtered using these coefficients in order to ascertain a near field component in the microphone signals, which is taken as the component of the own voice of the wearer. The use of at least two microphones is necessary in this case in order, when ascertaining the filter coefficients, to be able to use the definition of one of the microphones as a reference microphone to eliminate a dependency on the signal powers, which could lead to corruptions and hence to misjudgments regarding a voice activity of the wearer.
Published patent application US 2014/0088966 A1 proposes ascertaining an own voice activity of a wearer of a communication device on the basis of the differences in the sound pressure, which bring about different sound signals at two microphones of the communication device. The microphones are in this case arranged at such a distance from one another that a voice signal of the wearer has a sufficiently high difference in the sound pressure with which the voice signal strikes the two microphones.
U.S. Pat. No. 9,094,766 B2 and its counterpart European published patent application EP 2 242 289 A1 propose recognizing a voice activity of the wearer in a hearing device having two microphones on the basis of the coefficients of an adaptive filter, wherein an input signal for the adaptive filter is formed by one of the two microphone signals, but wherein the error signal used as reference variable is ascertained on the basis of the other microphone signal by virtue of the compensation signal produced in the adaptive filter being subtracted therefrom. The voice activity is then determined on the basis of normalized magnitudes of the filter coefficients.
U.S. Pat. No. 9,210,518 B2 and its counterpart European published patent application EP 2 040 486 A2 describe the determination of a voice activity of a hearing device wearer on the basis of collation of a fundamental frequency ascertained from two directionally processed microphone signals with one of the two unprocessed microphone signals. Published patent application US 2013/0275128 A1 proposes ascertaining the own voice activity of a wearer of a communication device on the basis of only one microphone signal by means of static methods, this involving a transfer function for the sound path from the mouth of the wearer to the microphone being modeled.